后面是over the past few weeks是什么时态

题目

后面是over the past few weeks是什么时态
The condition of the patient______stable over the past few weeks.
A.become
B.had became
C.has become
D.has became

答案

选C
首先become的完成时形式应该还是become,另外over the past few weeks的意思是“在过去的几周里”,是一个时间段,所以应该用现在完成时.